Slovenia’s electricity transmission system operator (TSO) ELES became a member of the European platform for cross-border exchange of balancing energy PICASSO. The company can purchase balancing energy from any provider from other countries within the network.
The Platform for the International Coordination of Automated Frequency Restoration and Stable System Operation (PICASSO) admitted its 14th operational member. ELES, Slovenia’s TSO, responsible for keeping electricity production equal to consumption, has accessed the European balancing energy market.
PICASSO optimizes balancing energy between control blocks in the Continental Europe synchronous area. It is necessary to keep the grid frequency at 50 Hz.
Automatic frequency restoration reserve, aFRR, is the second line of defense against grid imbalance
Ensuring the right production level is primarily the task of electricity suppliers. They purchase the energy that they expect their customers need for each 15-minute interval of the day. The amount is very difficult to predict accurately, especially in a network with tens of thousands of solar power plants for self-consumption. The final balancing is the responsibility of the system operator, in this case ELES.
To maintain balance, a TSO has several levels of balancing services available. The first is the so-called frequency containment reserve (FCR). It responds instantly to any frequency deviations. ELES takes the reserve on lease, as do other transmission network operators. Its share is 15 MW.
The second segment is the automatic frequency restoration reserve (aFRR). ELES leases 60 MW of reserve power on both sides. In the positive direction, assets such as battery energy storage systems (BESS) step in to cover power shortages. On the negative side, an industrial facility could increase consumption to absorb a surplus. It works the same the other way around. A battery system is charged with the surplus energy, and a factory ramps down or stops activity.
ELES gets access to hundreds of providers
PICASSO collects and rates bids for aFRR according to their prices, placing them into a common merit order list – CMOL.
With hundreds of new providers, ELES said it expects lower prices. It noted that it doesn’t mean balancing costs would decrease, arguing that they depend on many other factors. The platform works under a marginal pricing system, like the spot power market. Energy flows between countries are limited by cross-border transmission capacities, which the algorithm also takes into account.
PICASSO platform was launched in 2022. It is one of the last steps in the rollout of a joint European electricity market. System balancing services are the only incomplete segment.
Greece, Bulgaria may connect to rest of PICASSO region next year
Greece and Bulgaria are working together separately. As for the rest of the region that Balkan Green Energy News covers, Romania’s Transelectrica has delayed its accession to PICASSO by one year to April 2027, and Croatia has pushed back the date for Croatian Transmission System Operator (HOPS) to the second quarter of next year.
Hungary’s MAVIR is due to join in three months.
Slovenia to enter MARI soon
On July 15, ELES is connecting to the Manually Activated Reserves Initiative (MARI). It is the joint European platform for cross-border exchange of manual frequency restoration reserve (mFRR).
The service is activated if aFRR can’t handle the imbalance. ELES takes on lease 190 MW of mFRR in the positive direction and 92 MW on the negative side.
